American Express credit card number validation

Q

All credit card numbers issued by American Express must start with 34 or 37 and have 15 digits. For example, 346997719493686 is a valid American Express credit card number.

How to write a single regular expression to validate a American Express credit card number described above?

✍: FYIcenter.com

A

Here is the regular expression for American Express credit card number validation:

^3[47][0-9]{13}$

^ - begin of the string
3[47] - matches 34 or 37
[0-9] - any decimal digit
{13} - repeating 13 times
$ - end of the string

Click the button to test this regular expression here online:

2013-01-22, 4131👍, 0💬